The present invention relates to a flexible tool holder for burnishing cutters used in engraving machines.
Burnishing or cutting tools are mounted in a spindle of an engraving machine by means of fixed tool holders, referred to as cutter knobs, of various types. The burnishing process requires highly trained specialists for adjusting the entire engraving machine so as to control the exact downward pressure of the rotating cutting tool against the engraving material. If the material is not uniform in thickness or the table of the machine is not exactly flat, problems of cutting too deeply in the base metal or of missing spots completely can occur. In the known fixed holders, for adjusting the cutting tool the spindle is taken apart and put back together manually, to remove the spring holding a spindle. This is described in 1975 Sept./Oct. issue of "The Engravers' Journal", article "Burnishing: How to Get the Best Results". In accordance with another proposal disclosed in the article "Burnishing: Another Technical Problem Solved" in 1976 Jan./Feb. issue of the same magazine, a special clip is attached to the spindle, which compresses the spring so that the rotating cutting tool and the spindle are lowered. The clip is held in place by a lever screw which holds the spindle in position. This method, however, is complicated and difficult because of the pressure required to initially compress the spring tube. In both methods, the spindle must be lifted between characters engraved rather than depressed while engraving. Computers have also been used to measure the depth of rotating cutting tools; however, the operator must fine tune the cutting depth and downward pressure of the spindle to achieve the necessary delicate engraving pressure.